1. Field of the Invention
The present invention relates to a contactless switch structure that is suited to an ON/OFF switch performing switching operations between two predetermined actions such as lighting and extinction, or start and stop of an operating instrument, and that is particularly suited to a contactless switch without a plurality of contact points for switching operations.
2. Description of the Related Art
As a device for performing switching operations between two predetermined actions such as lighting and extinction, or start and stop of an operating instrument, an ON/OFF switch is widely used. In addition, recently, a contactless switch without a plurality of contact points for switching operations are widely used. A variety of improvements for the operability of the switch lever in the contactless switch have been attempted. The inventors proposed a contactless ON/OFF switch disclosed in JP2009-26509A. The contactless ON/OFF switch comprises a switch lever that is excellent in user-friendliness and can be tilted in an arbitrary direction. The contactless ON/OFF switch comprises a cylindrical member that has flexibility and stretchability and thus may be freely restored to the normal position. The contactless ON/OFF switch also comprises a base member and a rod member that has flexibility. A first end of the cylindrical member is fixed to the base member. The rod member is inserted into the cylindrical member. A first end of the rod member is fixed to an end portion of the cylindrical member that is not fixed to the base member. A second end of the rod member is protruded from the cylindrical member. When a bending force is directed on the free end (the end fixed to the first end of the rod member) of the cylindrical member, the cylindrical member and the rod member are bent. As a result, the end portion (a moving end portion) of the rod member protruded from the cylindrical member is moved toward the free end along the shaft line of the rod member or is tilted from the shaft line. The movement of the moving end portion of the rod member is the same regardless of the direction of the bending force directed on the free end. Thus, if the movement of the end portion is converted to electrical signal binary and is output, the same output can be obtained, that is, the ON/OFF operation can be provided.
The contactless ON/OFF switch, however, has a problem that care and costs are required for maintenance. For instance, a method of converting the movement of the moving end portion to electrical signal binary particularly prefers to use of reflecting light, but in use of the reflecting light, a decreased amount of the reflecting light leads to a change of the detection level of a light-receiving element. Accordingly, the contactless ON/OFF switch needs to be replaced if the amount of the reflecting light is decreased, thus requiring care and costs for maintenance.
Thus, the inventors further proposed a structure of a switch lever for a contactless ON/OFF switch disclosed in JP2010-123320A. The structure of the switch lever comprises a cylindrical member that has flexibility and stretchability and thus may be freely restored to the normal position. A first end of a rod member is inserted into the cylindrical member and fixed therein. A mirror surface is formed at an end of the rod member that is surrounded by the cylindrical member. A detector is opposed to the mirror surface. The amount of light on the light-receiving element is changed by a slant of the mirror surface formed at the end of the rod member. The detector detects the change on the basis of the amount of light received by the light-receiving element during startup. Namely, the detector resets the standard detection level at every startup. This reduces the affect of the aged deterioration of the mirror surface, thereby improving the durability of the switch. The structure can thus keep the operability that the switch lever can be tilted in any direction, while decreasing the frequency of breakdowns and thus decreasing care and costs required for maintenance.
Patent Literature 1: JP2009-26509A
Patent Literature 2: JP2010-123320A